SLC6A4 repeat and single-nucleotide polymorphisms are associated with depression and rest tremor in Parkinson’s disease
Jian-Yong Wanga,b,c,1, Qian-Ya Fana,1, Jia-Hui Heb, Shi-Guo Zhub, Chen-Ping Huangc, Xiong Zhangb,*, Jian-Hong Zhub,c,*
Introduction: Level of serotonin is mainly regulated by the serotonin reuptake transporter encoded bySLC6A4. The promoter region ofSLC6A4 bears a repeat polymorphism 5-HTTLPR and a single nucleotide polymorphism rs25531. We have previously studied the association between these two variants and sporadic PD. The objective of the current study was to determine whether theSLC6A4 polymorphisms were associated with key motor and non-motor symptoms of PD.
Methods: A total of 370 PD patients of Han Chinese were included. Associations between theSLC6A4 polymorphisms and PD symptoms including depression, intellectual impairment, tremor and rigidity were analyzed.
Results: 5-HTTLPR was associated with depression in PD patients and presence of the LL genotype was protective against the depression risk. The rs25531 was associated with rest tremor in PD and the A allele serves as a recessive risk allele. No associations were found in the two polymorphisms with respect to intellectual impairment and rigidity in the cohort.
Conclusion: The current study reveals two PD symptoms associated withSLC6A4 polymorphisms, and provides new insight into how serotonergic system genetically participates in the symptomatic progression of PD.